Your health is in your posture

Science

Published in 1991, the Neck Disability Index (NDI) was the first instrument designed to assess self-rated disability in patients with neck pain. This article reviews the history of the NDI and the current state of the research into its psychometric properties—reliability, validity, and responsiveness—as well as its translations. Focused reviews are presented into its use in studies of the prognosis of whiplash-injured patients as well as its use in clinical trials of conservative therapies for neck pain.

Background: Published in 1991, the Neck Disability Index (NDI) was the first instrument designed to assess self-rated
disability in patients with neck pain. This article reviews the history of the NDI and the current state of the research into its psychometric properties—reliability, validity, and responsiveness—as well as its translations. Focused reviews are presented into its use in studies of the prognosis of whiplash-injured patients as well as its use in clinical trials of
conservative therapies for neck pain.
Special Features: The NDI is a relatively short, paper-pencil instrument that is easy to apply in both clinical and
research settings. It has strong psychometric characteristics and has proven to be highly responsive in clinical trials. As of late 2007, it has been used in approximately 300 publications; it has been translated into 22 languages, and it is
endorsed for use by a number of clinical guidelines.
Summary: The NDI is the most widely used and most strongly validated instrument for assessing self-rated disability in patients with neck pain. It has been used effectively in both clinical and research settings in the treatment of this very common problem. (J Manipulative Physiol Ther 2008;31:491-502)
Key Indexing Terms: Neck Pain; Treatment Outcome; Reliability and Validity; Outcome Assessment (Health Care);
Spine; Cervical Vertebrae.
Vernon H. The Neck Disability Index: State-of-the-art, 1991-2008. Journal of Manipulative and Physiological Therapeutics. 2008 Sep;31(7):491-502. PubMed PMID: WOS:000259635600002.

SUMMARY: An often-suggested factor in the aetiology of craniomandibular disorders (CMD) is an anteroposition of the head. However, the results of clinical studies to the relationship between CMD and head posture are ontradictory. Therefore, the first aim of this study was to determine differences in head posture between well-defined CMD pain patients with or without a painful cervical spine disorder and healthy controls. The second aim was to determine differences in head posture between myogenous and arthrogenous CMD pain patients and controls. Two hundred and fifty persons entered the study. From each person, a standardized oral history was taken and blind physical examinations of the masticatory system and of the neck were performed. The participants were only included
into one of the subgroups when the presence or absence of their symptoms was confirmed by the results of the physical examination. Head posture was quantified using lateral photographs and a lateral radiograph of the head and the cervical spine. After correction for age and gender effects, no difference in head posture was found between
any of the patient and non-patient groups (P >0Æ27). Therefore, this study does not support the suggestion that painful craniomandibular disorders, with or without a painful cervical spine disorder, are related to head posture.
KEYWORDS: craniomandibular disorders, cervical spine disorders, head posture, neck pain, temporomandibular disorders.
Results
No difference in head posture measured on the photographs with the participant in a sitting or a standing position was found (t ¼ 1Æ64, P ¼ 0Æ10). Therefore, the meanvalues of thetwophotographswereused in further analysis. A significant positive correlation was found between the head posture measured on the radiograph and on the photographs (R ¼ 0Æ43, P ¼ 0Æ00). In Table 2 the mean values and standard deviations of the two angles used to quantify head posture are shown for the non-patient group, the group with a painful CMD, the group with a painful CSD and the group with a painful CMD and CSD. For both methods, no difference was found in head posture between the groups (see Table 3). For the photographs, increasing age was associated with a more anteroposition of the
head (t ¼ )2Æ39, P ¼ 0Æ02). No significant interactions between age and head posture were present. Table 4 shows the mean values and the standard deviations of the head posture for the non-CMD group, the group with a myogenous CMD, the group with an arthrogenous CMD and the group with a myogenous and an arthrogenous CMD. No ifference in head posture was found between the subgroups of CMD patients and the non-CMD patients and a positive age
effect was present for the photographs (Table 5). No interactions were present.
Visscher CM, De Boer W, Lobbezoo F, Habets L, Naeije M. Is there a relationship between head posture and craniomandibular pain? Journal of Oral Rehabilitation. 2002 Nov;29(11):1030-6. PubMed PMID: WOS:000179548100002.

The Relationship between Posture and Curvature of the Cervical Spine
ABSTRACT
Objective: To study the relationship between posture and curvature of the cervical spine in healthy subjects.
Subjects: The study was composed of 54 healthy students (25 men and 29 women) aged 20-31 yr with a mean
age of 24.7 yr.
Methods: Lateral radiographs were taken of the head and cervical spine of the subjects while standing in a
neutral position. Cervical spine posture was quantified by the angle of a reference line, composed of reference
points of the upper six cervical vertebrae, with the horizontal axis. The curvature of the cervical spine was
classified visually as lordotic, straight or reversed.
Results: A relationship was found between posture and curvature of the cervical spine (p = .006); a more
forward posture of the cervical spine was related to a partly reversed curvature; and a more upright posture was
related to a 1ordotic curvature. Moreover, men more often exhibited a straight curvature, and women more
often exhibited a partly reversed curvature.
Conclusion: The curvature of the cervical spine is related to the subject's posture and gender. (J Manipulative
Physiol Ther 1998; 21:388-91).
Key Indexing Terms: Cervical Spine; Gender; Posture
Visscher CM, de Boer W, Naeije M. The relationship between posture and curvature of the cervical spine. Journal of Manipulative and Physiological Therapeutics. 1998 Jul-Aug;21(6):388-91. PubMed PMID: WOS:000075676000002.

Abstract
The purpose of the present experiment was to investigate the effects of cervical muscular fatigue on postural control during quiet standing under different conditions of reliability and/or availability of somatosensory inputs from the plantar soles and the ankles and visual information. To this aim, 14 young healthy adults were asked to sway as little as possible in three sensory conditions (No vision, No vision-Foam support andVision) executed in two conditions of No fatigue and Fatigue of the scapula elevator muscles. Centre of foot pressure (CoP) displacements were recorded using a force platform. Results showed that (1) the cervical muscular fatigue yielded increased CoP displacements in the absence of vision, (2) this effect was more accentuated when somatosensation was degraded by standing on a foam surface and (3) the availability of vision allowed the individuals to suppress this destabilizing effect. On the whole, these findings not only stress the importance of intact cervical neuromuscular function on postural control during quiet standing, but also suggest a reweigthing of sensory cues in balance control following cervical muscular fatigue by increasing the reliance on the somatosensory inputs from the plantar soles and the ankles and visual
information.
Results of the present experiment showed that (1) the cervical muscular fatigue yielded increased CoP displacements in the absence of vision, (2) this effect was more accentuated when somatosensory information was disrupted by standing on a foam surface and (3) the availability of vision allowed the individuals to suppress this destabilising effect. On the whole, these findings not only stress the importance of intact cervical muscle function on postural control during quiet standing, but also suggest a reweigthing of sensory cues in balance control following to cervical muscular fatigue by increasing the reliance on the somatosensory inputs from the plantar soles and the ankles and visual information.
Finally, we would like to mention that some subjects reported sensation of cervical pain at the end of the fatiguing exercise. Indeed, pain often develops following fatiguing muscle contractions. This sensation probably arises from firing of the groups III and IV afferents, that are sensitive to metabolites and inflammatory substances (e.g., potassium, lactic acid, bradykinin and arachidonic acid) accumulated within the muscle during activity to fatigue (e.g., ). There is thus a possibility that pain per se might affect postural control. Such a proposal is yet speculative and warrants additional investigations.
Vuillerme N, Pinsault N, Vaillant J. Postural control during quiet standing following cervical muscular fatigue: effects of changes in sensory inputs. Neuroscience Letters. 2005 Apr 22;378(3):135-9. PubMed PMID: WOS:000228112600003.

Objective: While sensorimotor alterations have been observed in patients with neck pain, it is uncertain whether
such changes distinguish whiplash-associated disorders from chronic neck pain without trauma. The aim of this
study was to investigate head steadiness during isometric neck flexion in subjects with chronic whiplash-associated
disorders (WAD), those with chronic non-traumatic neck pain and healthy subjects. Associations with fatigue and ef-
fects of pain and dizziness were also investigated.
Methods: Head steadiness in terms of head motion velocity was compared in subjects with whiplash (n = 59), non-traumatic neck pain (n = 57) and healthy controls (n = 57) during 2 40-s isometric neck flexion tests; a high load test and a low load test. Increased velocity was expected to reflect decreased head steadiness.
Results: The whiplash group showed significantly decreased head steadiness in the low load task compared with the other 2 groups. The difference was explained largely by severe levels of neck pain and dizziness. No group differences in head steadiness were found in the high load task.
Conclusion: Reduced head steadiness during an isometric holding test was observed in a group of patients with whip-
lash-associated disorders. Decreased head steadiness was related to severe pain and dizziness.
Key words: whiplash; isometric hold; head steadiness; neck
pain; dizziness.
J Rehabil Med 2010; 42: 35–41 Correspondence address: Astrid Woodhouse, Department of Public Health & General Practice, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), NO-7489 Trondheim, Norway. E-mail: astrid.woodhouse@ ntnu.no Submitted December 12, 2008; accepted October 7, 2009

Abstract
Patients with whiplash associated disorders (WAD) have shown less accuracy in trajectory head
motion compared to asymptomatic controls, which comply with clinical observations. The aim of this study was to
investigate whether a trajectory head movement task can differ between WAD patients, chronic non-traumatic neck
pain (CNP) patients and asymptomatic controls. Study groups included subjects with WAD (n = 35) with persistent neck pain after a car accident, CNP (n = 45), and asymptomatic controls (n = 48). Head motion was recorded from an unsupported standing position using a 3D Fastrak device. A laser pointer was attached to the head and by moving the head the subjects were asked to trace a figure of eight displayed on the wall at three different paces (slow, moderate and fast). The motion signal was decomposed into 1 Hz frequency bands and angular velocity (deg/s) within each frequency band was calculated. Significantly higher angular RMS velocity was found in the WAD group compared to the two other groups for the slow paced test (3–4 and 4–5 Hz frequency bands) and the moderate paced test (3–4 Hz frequency band) indicating irregular and uncoordinated movements. Angular RMS velocity was associated with pain and dizziness, but only with severe symptom levels. In conclusion, irregular head movements during a complex task were found in the WAD group, indicating altered central sensorimotor processing. The irregularities were found within frequency levels observable to clinicians.
Conclusions
In a trajectory movement task, a group of whiplash patients showed a consistent lack of movement smoothness when
compared to CNP patients and asymptomatic controls. The movement irregularities were most evident in the 3–5 Hz
frequency bands, and indicate that such irregularities may well be observable to clinicians when examining these
patients.
Astrid Woodhouse, Ottar Vasseljen, Øyvind Stavdahl
Received: 11 August 2009 / Accepted: 23 September 2009 / Published online: 10 October 2009, Springer-Verlag 2009

Background: Persistent whiplash associated disorders (WAD) have been associated with alterations in kinesthetic sense and motor control. The evidence is however inconclusive, particularly for differences between WAD patients and patients with chronic non-traumatic neck pain. The aim of this study was to investigate motor control deficits in WAD compared to chronic non-traumatic neck pain and healthy controls in relation to cervical range of motion (ROM), conjunct motion, joint position error and ROM-variability.
Methods: Participants (n = 173) were recruited to three groups: 59 patients with persistent WAD, 57 patients with chronic non-traumatic neck pain and 57 asymptomatic volunteers. A 3D motion tracking system (Fastrak) was used to record maximal range of motion in the three cardinal planes of the cervical spine (sagittal, frontal and horizontal), and concurrent motion in the two associated cardinal planes relative to each primary plane were used to express conjunct motion. Joint position error was registered as the difference in head positions before and after cervical
rotations.
Results: Reduced conjunct motion was found for WAD and chronic neck pain patients compared to asymptomatic subjects. This was most evident during cervical rotation. Reduced conjunct motion was not explained by current pain or by range of motion in the primary plane. Total conjunct motion during primary rotation was 13.9° (95% CI; 12.2–15.6) for the WAD group, 17.9° (95% CI; 16.1–19.6) for the chronic neck pain group and 25.9° (95% CI; 23.7–28.1) for the asymptomatic group. As expected, maximal cervical range of motion was significantly reduced among the WAD patients compared to both control groups. No group differences were found in maximal ROM-variability or joint position error.
Conclusion: Altered movement patterns in the cervical spine were found for both pain groups, indicating changes in motor control strategies. The changes were not related to a history of neck trauma, nor to current pain, but more likely due to long-lasting pain. No group differences were found for kinaesthetic sense.
Astrid Woodhouse* and Ottar Vasseljen
Address: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), N- 7489 Trondheim, Norway

In this article, a systems approach to the development of posture control across the life span and its integration with voluntary tasks such as walking is described.
Research shows a clear cephalocaudal gradient in the development of postural responses. Postural muscle synergies develop appropriate temporal organization through experience in each new level of postural skill development. Sensory inputs contributing to posture control influence postural responses very early in development, with responses being elicited by vision alone, or by somatosensoy and vestibular cues in isolation. Studies of older adults indicate small, but significant, increases in onset latencies and disruptions in the temporal organization of postural muscle responses when subjects are given external threats to balance. In addition, older adults, like young children, use antagonist muscles more open in coactivation with agonist muscles. Older adults also have more difficulty balanc-
ing when sensory inputs are reduced experimentally or pathologically. Ankle dorsiflexor muscle weakness is also a factor in balance dysfunction in the older adult.
Summary and Conclusions
These studies on the development of posture control across the life span and its integration with voluntary tasks
such as walking show a number of interesting principles of developmental progression. First, infants show a clear cephalocaudal gradient in the development of postural responses, with control first appearing in the muscles of the neck, then the trunk, and finally the legs. Data show that postural muscle synergies develop appropriate temporal organization through experience in each new level of postural skill development. Muscle strength changes may also contribute to the development of postural control, but few data are available on this aspect of postural development. We believe sensory inputs contributing to posture control may be able to influence postural responses very early in development, with postural responses being evident if influenced by vision alone, or by somatosensory and vestibular cues in isolation. Studies on the older adult indicate small, but significant, increases in the onset latencies and disruptions in the temporal organization of postural muscle responses when subjects are given external threats to balance. In addition, older adults, like young children, use antagonist muscles more often in coactivation with agonist muscles when balancing. Older adults also have more difficulty balancing when sensory inputs contributing to balance control are reduced, so that they have less redundancy of sensory information. Thus, when both somatosensory and visual inputs are made in congruent with postural sway, the older adult shows significantly increased sway compared with the young adult, and many older adults lose balance completely. This characteristic is also similar to that seen in young children. Muscle (ie, ankle dorsiflexor) weakness may also be a factor in balance dysfunction in the older adult. Given the many similarities in functional capabilities of the different systems contributing to balance control in the child and the older adult when compared with the young adult, do these results support the strict vertical hierarchy hypothesis [hat as children mature, higher nervous system tenters take over function from more primitive reflex systems, and that as adults age and higher centers deteriorate, lower-level systems begin to show functions that reemerge? A though there are limited data to show that there is some emergence of spinal reflexes in the older adult, all other similarities in function between the different musculoskeletal and nervous subsystems can be explained by developmental changes in functional status of each system independently. There is no need to invoke the existence of a strict vertical hierarchy. For example, the similarities in use of antagonist muscles along with agonists in posture control in the two age groups (children versus older adults) simply imply that each may use the agonist-antagonist coactivation to stiffen the ankle joint and thus limit the degrees of freedom needed for postural control. This is a typical strategy found in any motor skill when function is not optimal; it is not an indication of a "lower level" of the vertical hierarchy reemerging in dominance. The systems model can be used to evaluate changes in the different systems contributing to balance control across the life span by asking questions such as: When the function of one system contributing to balance control is unavailable, what other systems can compensate? Are there specific environmental conditions that threaten balance control when specific systems are impaired, and can these conditions be avoided? and Can balance strategies be modified to improve balance function when a specific system is no longer functioningat optimal levels? Thus, this model has great flexibility and great potential in contributing not only to our understanding of balance changes across the life span, but to therapeutic interventions in the child or the older adult with balance dysfunction. However, our understanding of the clinical implications of many of the experimental findings has only recently been explored. As a result, effective approaches to assessment and treatment of some types of postural problems identified through systems research are still limited.
[Woollacott MH, Sbumway-Cook A. Changes in posture control across the life span--a systems approach. Phys Ther. 1990; 70: 799407.1

Abstract
Lesions in the cerebellum produce various symptoms related to balance and motor coordination.
However, the relationship between the exact topographical localization of a lesion and the resulting symptoms is not
well understood in humans. In this study, we analyzed 66 consecutive patients with isolated cerebellar infarctions
demonstrated on diffusion-weighted magnetic resonance imaging. We identified the involved lobules in these
patients using a cross-referencing tool of the picture archiving and communication system, and we investigated
the relationships between the sites of the lesions and specific symptoms using χ2 tests and logistic regression
analysis. The most common symptoms in patients with isolated cerebellar infarctions were vertigo (87%) and
lateropulsion (82%). Isolated vertigo or lateropulsion without any other symptoms was present in 38% of
patients. On the other hand, limb ataxia was a presenting symptom in only 40% of the patients. Lateropulsion, vertigo, and nystagmus were more common in patients with a lesion in the caudal vermis. Logistic regression
analysis showed that lesions in the posterior paravermis or nodulus were independently associated with lateropulsion. Lesions in the nodulus were associated with contralateral pulsion, and involvement of the culmen was associated with ipsilateral pulsion and isolated lateropulsion without vertigo. Nystagmus was associated with lesions in the pyramis lobule, while lesions of the anterior paravermis were associated with dysarthria and limb ataxia. Our results showed that the cerebellar lobules are responsible for producing specific symptoms in cerebellar stroke patients.
Conclusion
With MRI and clinical data obtained from patients with isolated cerebellar infarctions, we determined lobular
localization of cerebellar lesions using a PACS system and statistical analyses. Our results showed that vertigo and
lateropulsion are the most common symptoms of isolated cerebellar infarctions. Our findings also suggest that
contralateral pulsion was associated with lesions involving the nodulus, while ipsilateral pulsion was associated with
lesions involving the culmen. Nystagmus was associated with lesions in the pyramis lobule, while dysarthria and
limb ataxia were associated with lesions of the anterior paravermis.
Ye BS, Kim YD, Nam HS, Lee HS, Nam CM, Heo JH. Clinical Manifestations of Cerebellar Infarction According to Specific Lobular Involvement. Cerebellum. 2010 Dec;9(4):571-9. PubMed PMID: WOS:000284955800011.

Study Design. A prospective clinical study.
Objective. To quantitatively evaluate impairment of postural stability in patients with cervical myelopathy. Summary of Background Data. Proprioceptive sensation plays an important role in coordinated movement of the lower extremities and postural stability. Nevertheless, although disturbance of proprioceptive information will have an influence on the maintenance of postural stability, there have been few studies dealing with deterioration of postural stability in patients with cervical myelopathy.
Methods. We investigated 52 cervical myelopathy paients who could stand without support and compared the
results with those of 29 age-matched healthy volunteers. Postural stability was examined using a stabilometer. In the
stabilometer, sway of gravity center was measured at upright position with eyes closed for 30 seconds. We used 2
parameters for evaluation: environmental area (EA), which measures degree of sway of the gravity center, and locus
length per environmental area (L/EA), which measures fine control of standing posture by proprioceptive reflexes.
Results. The mean EA of the patient group was 13.9, whereas that of the control group was 2.74, revealing signifi-
cantly larger postural instability in the patient group compared to the control group. The L/EA of the patient group was significantly worse than the control group. It was also shown that postural instability was significantly larger in the myelopathy patients with the severe clinical symptoms.
Conclusion. The results of the present study demonstrate impairment of postural stability in patients with cervical myelopathy. The stabilometer can objectively evaluate the postural stability, which may reflect the function of the dorsal columns and the corticospinal tracts. Thus, stabilometry is a useful method for measuring a part of proprioceptive function and for objective assessment of the lower limb function of cervical myelopathy.
Yoshikawa M, Doita M, Okamoto K, Manabe M, Sha N, Kurosaka M. Impaired postural stability in patients with cervical myelopathy - Evaluation by computerized static stabilometry. Spine. 2008 Jun 15;33(14):E460-E4. PubMed PMID: WOS:000256837500020.